With increasing miniaturization of device pattern due to advancements in semiconductor manufacturing technologies, a cleaning technique for removing minute contaminant particles from semiconductor substrate is desired.
A conventional two-fluid jet cleaning device used as a single wafer cleaning device removes particles by rotating a wet semiconductor substrate and spraying mist-like droplets (droplet mist) generated by mixing gas such as dry air or nitrogen and liquid such as pure water to the surface of the semiconductor substrate.
A freeze cleaning process is known as a method for removing particles on a semiconductor substrate. In a conventional freeze cleaning process, first, pure water is supplied on a semiconductor substrate and a part of the pure water is splashed out of the substrate by rotating the semiconductor substrate, so that a liquid film (water film) is formed on the semiconductor substrate. Then, coolant gas is discharged to the semiconductor substrate to freeze the liquid film and particles are captured by a frozen film (ice film) by using volume expansion force generated when the phase of the liquid film changes from liquid to solid. Thereafter, pure water is supplied to the semiconductor substrate to melt the frozen film and the particles are discharged from the semiconductor substrate along with the pure water.
However, in such a conventional freeze cleaning process, there is a problem that fine patterns on the semiconductor substrate are damaged by the volume expansion force of the liquid.